It’s a common sight on casino floors: patrons jumping from slot machine to slot machine before eventually hunkering down at a game that’s due for the next big payout.
But can players – even the regulars who frequent a particular property – really tell the difference between the house edge on one game from that of another?
Nope. At least not according to a series of recent studies led by Anthony Lucas, a UNLV Hospitality College professor and former gaming industry operations analyst.
For the past several years, Lucas and colleague Katherine Spilde from San Diego State University have taken to casino floors on multiple properties in the U.S., Australia, and Mexico to investigate.
Their results contradict long-held beliefs by casino operators about a player’s ability to detect differences in how much – and how often – a slot machine pays.
“I think some operators are naturally and understandably cautious of new information that challenges traditional industry practices,” said Lucas.
“But we must consider how we know what we know.
This is where our work takes on a Moneyball-like aspect – questioning the wisdom of widely held beliefs when data show that a new way of thinking may be better.”
In their latest study, the UNLV-led research team compared two pairs of reel slot games at a “locals” casino in suburban Sydney, Australia, where all wagering occurs on electronic gaming devices.
Their process is relatively straightforward: take two identical slot machines, positioned in similar places on a casino floor, but vary the par – the percent of total coin-in that the machine keeps over time.
For example, if the par on a game is set at 10 percent, the machine would be expected to retain $10 of every $100 wagered, on average, over the long term.
But in the short term, this rarely happens, increasing the difficulty of par detection.
For this study, researchers compared the daily performance of pairings for the games “Tokyo Rose” and “Dragon’s Fortune X” over a nine-month period.
The pars within each pairing ranged from 7.98 percent on the low end to 14.93 percent on the high end.
Researchers measured daily coin-in for each machine as well as its T-win, a formula that multiplies coin-in and par to calculate a machine’s expected value, or its theoretical win.
If over the course of the nine-month test, regular players could detect a difference in the pars, this comparison would reveal whether (and how much) players migrated from higher par to lower par games.
As Lucas predicted, differences between the high and low par games remained stable throughout the length of the study, which meant that there was no statistically significant indication of play migration.
And while the lower par machines had more coin-in over the course of the study period, the T-win was greater on average for the high par machines.
The positive impact from the elevated T-win on revenue for the higher par machines more than compensated for the decline in coin-in on those machines.
“Casino operators should take note of the substantial increases in T-win, as they are responsible for optimizing revenues, not coin-in,” said Lucas.
The results were also consistent with findings from the team’s previous studies, which analyzed 11 pairs of games over 180 days at gaming properties in U.S., Mexico, and Australia.
So, other than busting one of gaming’s great myths, why does this matter?
Pars are an important factor for casinos looking to optimize revenues, as the bulk of slot revenues come from reel slots, and a lion’s share of a casino’s overall profits come from slot operations. While there are exceptions to this rule, it is true for most of the world’s casinos.
“Ultimately, operators are responsible for optimizing slot revenues, which is no simple task,” Lucas said.
“Knowing which par will produce the greatest win is most helpful, but the optimization issue becomes more complex when the possibility of player detection is introduced.”
That’s where industry perspective is mixed, as operators have expressed concerns that short-term gains from higher pars could lead to long-term losses as players leave perceived “tight” slot floors for the greener pastures of their competitors.

As Lucas predicted, differences between the high and low par games remained stable throughout the length of the study, which meant that there was no statistically significant indication of play migration. Image is in the public domain.
To account for this concern, researchers extended the length of time from previous work, from six months to nine months.
They also expanded the difference in pars between matched pairs from 4.9 percent in the initial study to 6.95 percent in the current study.
In a concurrent study, the researchers compared the Australian data with four, two-game pairings at two similarly situated casinos in Mexico.
Par differences for those games were even more drastic – ranging from 7.98 to 8.9 percent.
Despite these factors, in both instances, the results still found no evidence of players moving away from higher-par machines to their low-par counterparts, and the high-par games continued to post substantially greater revenues.
“Put simply, our results suggest that greater pars produce greater revenues, without the risk of brand damage resulting from ‘price’ detection,” Lucas said.
Slots Pay Out How Much Each Day in Vegas?
The Nevada Gaming Control Board found that in 2017 there were 38,434 slots in operation across 40 locations on the Las Vegas Strip. It was estimated that those machines generated revenues worth $269,527,000 per month.
That equates to an average slot generating $226 per day.
This figure is even more startling when you consider that most slot machines have an RTP (return to player) over 90%.
The average slot pays out at a rate of 93-94%. That gives an insight into how much money is pumped into the machines each day.
It should be noted that these figures might be for Las Vegas but it is a trend that echoes around the world.
The RTP is dependent on the manufacturer rather than the casino. Slots developers can set a range for the RTP but the casinos must stick to offering an RTP within that range.
It’s All About the RTP
If you’re looking for slot machines that are most likely to hit, then you want slots that have the highest percentage of RTP. Essentially, the higher the RTP percentage, the more likely the slot is to pay out.
How is RTP calculated?
Well, if you take a slot that has an RTP of 94% then the theory is that if you put $100 into the slot then you could expect an estimated return in winnings of $94 (over a long period of time).
Obviously, that’s a rough guide and is not the case for every player.
Another way to work out where to find the loosest land-based slots is to scan message boards and threads online.
The likes of TripAdvisor forums and Reddit often have slots players sharing their experiences of trips to places such as Las Vegas, Atlantic City, and Macau.
These players will then often highlight slots at casinos where they have enjoyed decent pay outs.
If you don’t want to spend time trawling threads looking for online slots with the best payouts, a great place to look is on comparison sites that offer independent online slots reviews. You’ll find slots with the best RTPs as well as a list of the online casinos offering the games and, best of all, you don’t have to lift a finger.
You’ll find slots with the best RTPs as well as a list of the online casinos offering the games and, best of all, you don’t have to lift a finger.
Progressive Jackpots FTW
One of the big draws of slot machines is the fact that they can create millionaires in an instant. Progressive jackpots online offer prize money that is on a par with national lottery games.
On September 28, 2018, a record-breaking progressive jackpot win of €18,915,721 was triggered by an anonymous player on the Mega Moolah slot by Microgaming at Grand Mondial online casino.
It’s paid out over a whopping €874 million since it began.
A number of other slot machines have paid out crazy sums of cash in the past.
On January 20, 2013, an anonymous player won €17,860,868 on the Mega Fortune slot by NetEnt at the Finland-based Paf Casino.
Online progressive jackpots are crazy popular because the minimum bet values are lower than at land-based casinos and the convenience of accessing them remotely or on the go makes them more appealing than trekking from casino to casino by foot.
Progressive jackpots are not restricted to online slots, though. The largest ever payout on a slot machine came back on March 21, 2003, when a 25-year-old engineer from Los Angeles triggered a jackpot worth $39,710,826 on the Megabucks slot at the Excalibur casino.
The Megabucks slot has also paid out sums of $34,955,489 to Cynthia Jay-Brennan on January 26, 2000, at the Desert Inn casino. $27,570,879 to a 67-year-old retired flight attendant at the Palace Station on November 15, 1998, and $22,618,156 to Johanna Huendl at Bally’s on March 27, 2002.
You are more likely to win on a game with a smaller jackpot over these huge progressives, however, it’s still possible to get lucky and scoop a massive cash prize off just one spin.
Picking the Right Games
For players starting afresh, a fair bit of research will be required to find out where to find the slots most likely to hit.
It won’t take long before certain trends start to appear. Slots by the same developers constantly being mentioned, certain casinos being identified as possessing loose slots, and slot machines by name that have proven to be big earners for players.
Online software developer Playtech has a reputation for releasing slots with high RTP percentages.
Slots such as Goblin’s Cave, Ugga Bugga, and Ocean Princess all offer above average RTP.
Other developers such as Barcrest, WMS, and NetEnt are also renowned for their slots with high RTP.
On the flip side, it will also be worth taking note of the slots that are notorious for not paying out.
The more slots you can add to a blacklist of bad earners helps to narrow down the slots that can be labelled for their higher payouts.
A number of slots have been highlighted by players as games to avoid due to their low RTP. The likes of Wish Upon a Jackpot by Blueprint Gaming, Adventures in Wonderland by Ash Gaming, and King Kong by Cryptologic frequently appear on such lists.
Slots are a beast in their own right. You can spend all day playing the slots with the highest RTP and get nothing. Then you could have two spins on a slot that is reputedly dry as a bone and hit a big payout. Sometimes the only way to find out what works and what doesn’t is to get out there and spin those reels yourself.
Source:
University of Nevada Las Vegas
Media Contacts:
Tony Allen – University of Nevada Las Vegas
Image Source:
The image is in the public domain.
Original Research: Closed access
“Impacts of increased house advantages on reel slots”. Anthony F. Lucas.
International Journal of Contemporary Hospitality Management. doi:10.1108/IJCHM-07-2018-0577